Lesson 6

I Scream for Macro-Core®

I get this question alot from all sorts of people. They ask; "What's the difference between Macro-Core® samples and good old fashioned split-spoon (split-barrel) samples." Well, let's give this explanation a shot.

First, Macro-Core® samples are taken in 5, 4, 3, or 2 foot lengths ( or 1 meter for you metric guys). MC samples are roughly 1.5" in diameter and are taken from a 2.125" diameter direct push hole. Obtaining MC samples produces no cuttings. Potential cross contamination is minimized as the only part of the sampler that touches the soil sample is the shoe, which is easily decontaminated. Samples are recovered in liners made of PVC, Teflon®, PETG, or Stainless Steel. Samples can be removed from the liners in the field or the liners can be capped for transport to a laboratory. The MC sampler can be run in either open tube sampling or closed-tube sampling to ensure discrete sample recovery.  For you geotechnical guys, MC samples are NOT undisturbed.  However, you can collect samples of the recovered MC sample for physical property testing, such as moisture content, grain size analysis, plasticity characteristics, classification and remolded testing to name a few. 

Now, we all know that the split spoon is generally used while performing the Standard Penetration Test, but the MC sampler is NOT used with SPT.  Dynamic penetration or CPT can be performed if you need that type of data.

Just about any type of unconsolidated material (I mean not rock) can be collected; clays, silts, sands, glacial deposits, sediment, and even weathered shales and weathered sandstones.  Boulders, cobbles, dry coarse gravel, and competent rock are on the no-no list. 

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